| 摘要 |
PROBLEM TO BE SOLVED: To improve the precision in measurement while forming a light path of laser beams inside and preventing distortion of a movable part of a telescopic light guide part in an optical length measuring machine using laser beams. SOLUTION: The space between cylinders 16 and 18 inside/out of the light guide part 14 is divided into two parts in the axial direction by a piston 42 to form first and second pressure chambers 44 and 46. Difference in the pressure is generated between the two pressure chambers 44 and 46 so that the force in the axial direction is generated. As the piston 42 is in the axially symmetrical shape, the line of action of the force generated from the difference in pressure is on the axis line and the moment will not be generated. Accordingly, distortion caused by the moment is not generated in the movable part of the light guide part, and the high precision in measurement is compensated. COPYRIGHT: (C)2003,JPO
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